Oscillatory drive mechanism



OSCILLATORY DRIVE MECHANISM 2 Sheets-Sheet 1 Filed Sept. 28, 1953 INVENTOR. ALBERT E. SILER By CHARLES T. WILSON,JR

ATTORNEY Dec. 4, 1956 A. E. SILER ETAL OSCILLATORY DRIVE MECHANISM 2 Sheets-Shet 2 Filed Sept. 28,- 1953 INVENTOR. ALBERT E. SILER CHARLES T. WILS'ON, JR.

ATTORNEY United States Patent OSCILLATORY DRIVE MECHANISM Albert E. Siler, Compton, and Charles T. Wilson, In,

Los Angeles, Calif., assignors to North American Aviation, Inc.

Application September 28, 1953, Serial No. 382,602 10 claims. or. 74--86) This invention relates to a mechanism for imparting movement to an associated device and more particularly, to a drive mechanism which is capable of selectively performing either of two functions: imparting high-frequency, conical or oscillatory motion to an antenna reflector or maintaining the antenna reflector in a neutral position.

The advent of radar and its many associated problems was the genesis of a new series of mechanical devices. The basic problem has been to manipulate various antenna configurations through scanning patterns contrived so as to adequatley search a given solid angular region in space. One of the more desirable patterns emergent from scanning studies involves the superposition of a highfrequency, vertically oscillatory scan over a low-frequency, horizontal oscillatory scan to produce a composite sine scan of the region in question. Generally, it is thought desirable to scan by moving the radar reflector through the desired path rather than by moving the wave guide because of the precision with which the design dimensions of the wave guide must be maintained in order to obviate undue attenuation of energy conducted thereby. The scanning system in which the antenna reflector is moved is, however, fraught with dynamic balancing problemsdue to the relatively large inertia of the reflector.

The design problem breaks down into two separate problems: one concerned with a drive mechanism that will manipulate the reflector in such a fashion as to describe the desired scanning pattern and the other concerned with producing a reflector drive unit of such characteristics that there will be no reactive effects reflected on to the supporting frame. The former problem is generally further complicated by the requirement that it should be possible to quickly switch from search to track and vice versa; the tracking orientation of the reflector being a prescribed neutral position defined as the neutral radial axis about which oscillation occurs.

Heretofore the scanning pattern has usually been modi tied in order to simplify the mechanical and dynamical problems involved. By compromising the selection of the scanning pattern and using a high-frequency conical scan in combination with a low-frequency horizontal scan, it 1s possible to evolve a satisfactory design solution. This in- "ice crating unbalanced forces that would react on the supporting frame.

It is therefore an object of this invention to provide an oscillatory drive mechanism adapted to impart a highf-requency, oscillatory motion to an associated device.

Another object of this invention is the provision of a drive mechanism adapted to impart a conical motion to an associated device.

Still another object of this invention is the provision of an oscillatory drive mechanism adapted to maintain an associated device in an immobile, accurately-positioned neutral position.

It is a further object of this invention to provide an oscillatory drive mechanism adapted to perform one of two alternative functionsat the instigation of an operator; either impart a high-frequency, oscillatory motion vention carries forward the design to a solution resulting in a system that accomplishes the exaetIp-rogramming desired (i. e., the aforementioned sine scan) in combination with a satisfactory dynamical solution by providing for the required high-frequency vertically oscillatory scan.

This invention contemplates not only a device capable of imparting to an associated device high-frequency, oscillatory motion but is'also capable of maintaining an associated device in a neutral or tracking position.

This invention also contemplates a device which may be readily switched from one of the above-described functions to the other.

This invention further contemplates a mechamsm Which will impart to an associated device a conical motion.

This invention also contemplates a mechanism which will perform the above-described functions without gento an associated device, or maintain the associated device in an immobile, neutral position.

It is a still further object of this invention to provide an oscillatory drive mechanism adapted to perform one of two alternative functions at the instigation of an operator: either impart a conical motion to an associated device, or maintain the associated device in neutral position.

Still another object of this invention is the provision of an oscillatory drive mechanism in which the sequential rotative functions, from the constant angular velocity input up to a yoke structure for converting rotative motions to oscillatory motions, operate at a constant angular velocity without regard as to which of two alternative output functions has been selected by the operator: imparting a high-frequency, oscillatory motion to an associated device, or maintaining the associated device at an immobile neutral position.

It is a still further object of this invention to provide an oscillatory drive mechanism of such an axially symmetrical confi'guration as to preclude the generation of unbalanced forces that would react on the supporting frame.

It is a further object of this invention to provide an oscillatory drive mechanism which can be rapidly switched between the performance of two alternative functions: either imparting a conical or an oscillatory motion to an associated device, or maintaining the associated device in neutral position.

Other objects of invention will become apparent from the following description taken in connection with the accompanying drawings, in which Fig. 1 is a rear elevational view of the drive mechanism .of this invention showing its connection with a portion of a radar antenna reflector;

Fig. 2 is a longitudinal sectional view of the drive mechanism of this invention shown in a neutral position;

Fig. 3 is an elevational view of a portion of the mechanism of Fig. 2 shown in a position for transmitting oscillatory motion to an associated device; V

Fig. 4 is a cross-sectional view taken along the lines 44 of Fig.- 2 and showing the cam arrangement thereof;

Fig. 5 is a top plan view of the cam arrangement shown in Fig. 4;

Fig. 6 is a cross-sectional view taken along lines 6--6 of Fig. 2; and

Fig. 7 is a detailed view of Fig. 6 showing the intersections of circles 52 and 53.

In detail referring to Fig. 2, the drive mechanism assemblage is contained within and attached to a housing structure generally designated 1. Secured to housing 1 is motor 2 connected by motor shaft 6 to pinion gear 3 for driving said pinion gear. Gear 3 may be supported on a shaft 4 which is journalled in sleeve bearing 5. Main gear 7 and auxiliary gear 8 are in turn meshed with pinion 3 for rotation about the primary axis 19 of the mechanism. Gears 7 and 8 have a differing number of teeth, for a purpose to be described, and are mounted on the aft end of sleeve 9; gear 7 being secured to'sleeve 9 as by key it while gear 8 is free to rotate on sleeve 9. The exterior, cylindrically shaped surface of sleeve 9 is mounted for rotation about axis 19 within housing 1 in roller bearings 13. At the end of sleeve '9 opposite gears 7, 8, dynamic balancing structure is secured thereto as by nut 16 threaded on the end of sleeve 9. Balancing structure 15 incorporates a noncontigucus series of steel balls 17 which are free to move within an annular race 18 symmetrically disposed'with respect to primary axis 1? of the mechanism. It has been found that the use of enough balls 17 to fill less than half of the length of race 18 gives satisfactory dynamic stabilization.

Cylindrical bearing surface 20 is formed within sleeve 9 about longitudinal axis 21 which is angularly disposed with respect to primary axis 19. Shaft 22 resides within bearing 20 being retained therein by snap ring 23 (ad jacent gears '7, S) and shoulder 24 (adjacent nut 16). The forward portion 11 of shaft 22 extends outwardly of sleeve 9 and shoulder 24 and is formed cylindrically concentric with primary axis 19 when in the position shown in Fig. 2. Rotatably mounted on forward portion 11 of shaft 22 is the body 14 of yoke structure 25 which is constrained between shoulder 24 and nut 26 threadedly secured to the forward end of forward portion 11. The outwardly extending arms 12 of yoke structure 25 contain coaxial bearings 27, 28 whose rotational axis 29 intersects axes 1%, 21 at a common point. in the orientation of the mechanism shown in Fig. 2, axis 29 is normal to primary axis 19 and lies in the plane of the drawing.

The end of shaft 22 adjacent gears 7, 8 is centrally bored to form rearwardly opening, cylindrical recess 39 concentric with axis 21. Located within recess 30 are helical compression spring 31, conical-headed piston detent 32, and the inner leg 33 of pawl structure 34. A cross-slot 59 is formed in the rearwardly directed end of. shaft 22 and the pawl structure 34 ispositioned therein, being held against the expansive force of spring 31 and pivotally mounted to shaft 22 by pin 35. Pawl structure 34 incorporates forwardly directed pawl stubs 36, 37 and rearwardiy directed cam rider stubs 38 and 39; Pawl stubs 36 or 37 can at the various times reside in pawl slot 42' formed in the rearwardly directed face of sleeve 9, thus effectively locking sleeve 9'and shaft 22 in either of two relative positions 180 apart. At other times, to be described, pawl stub 36 or 37 can be contacted by lands 4'1 formed on the rearwardly directed face of gear 8 and adapted to transmit rotation from gear 3 to pawl structure 34. Cam rider stubs 38 and 39 can at various times contact cams 42 and 43, respectively. As best seen in 4- cams 42, 43 are sectors of rings concentric with primary axis 19 and arepivotally mounted to housing 1 by pin 44-. Said cams are pivoted adjacent one end of their length and are spaced apart along their pivotal axis by spacers Contacting the sides of earns 42, 43 opposite pawl struc ture 34 is cam actuator 48 angularly disposed with respect to a vertical axis in Fig. 4 and incorporating forwardly extending bosses 49, 5%. Cam actuator 43 is supported for rotation on shaft 47 which extends outwardly of housing 1 for attachment to operating lever 46. A pair of helical compression springs 51 acting against washer 61 adjacent the rearwardly directed face of cam actuator 48 serve to hold bosses 49, 50 in contact with cams 42, 43. Depending upon the positions of bosses 49, 50 with respect to the pivotal axis of cams 42, 43, one of said cams may have its face directed into the path of travel of either cam rider stub 38 or 39 while the other cam is retracted and vice versa. Fig. 5 best shows cam 42 extended into the path of cam rider stub 38.

The orientation of the component parts shown in Fig. 2 is such that the axes 19, 21, and 29 intersect at a common point. In order for the mechanism to impart an oscillatory motion to an auxiliary device coupled to yoke 25 at bearings 27, 28, such auxiliary device must be constrained to have only one degree of angular freedomrotation about an axis 60 (Fig. l) which is normal to the axes 19 and 29 and which passes through their intersection. Fig. 1 shows such a device as antenna reflector 56 whose frame 55 is coupled to yoke structure 25 at bearings 27, 28 by pivot pins 58. Antenna 56 and its associated linkage 57 is supported for movement in only one plane-oscill-ation about axis 60.

In operation motor 2 drives gears 7, 8 through pinion 3 causing sleeve 9 to rotate at constant speed at all times. With shaft 22 locked in the position indicated in Fig. 2, by pawl stub 36 engaging pawl slot (cam 42 being in the forward position), the forward portion 11 of shaft 22 will rotate synchronously with sleeve 9. Since portion it is coaxial with axis 19 no motion will be induced in yoke structure 25. With a reflector 56 as the device coupled to yoke structure 25, it will be seen that said reflector will be maintained in a fixed neutral or tracking position.

As a prelude to a proper understanding of the operation of the device, whereby it can be manipulated so as to produce an oscillatory motion at the output yoke 25, to construction of the elements consisting of pinion gear 3, gears 7 and 8 will be elaborated. As was previously mentioned, gears 7 and 8 have a differing number of teeth; in the design shown namely 64 and 66 teeth, respectively. These are merely arbitrary values that have been used in a specific design, considerable latitude being permitted in the selection of the number of teeth assigned to each of the two gears so long as those numbers differ by a small amount. To achieve proper meshing and smooth running of gears 7 and 8 with pinion 33, said pinion is constructed with an extended addendum. Then by assigning the proper pressure angles to gears 7, 3 proper geometric contact can be achieved with pinion gear 3, even though the numbers of teeth in the two said gears dilfer.

This differing number of teeth causes a small differential motion between sleeve 9 keyed to gear 7 and gear 8 which is free to rotate on sleeve 9. If it is desired to switch from the tracking'position previously described to a condition where the mechanism imparts oscillatory motion to yoke 25 and sequentially antenna 56, lever 46 may be rotated switching the position of bosses 49, 5%} so as to raise cam 43 and lower cam 42. As pawl structure 34 is carried around by pawl stub 36 engaging pawl slot 40 in rotating sleeve 9, cam rider stub 39 contacts inner cam '43. As this rotation continues, pawl stub 36 is lifted free of pawl slot 43 and pawl stub 37 is forced into engagement with one of lands 41 formed in the face of gear 8. At this point, pawl structure 34 has pivoted about pin 35 a suflicient amount that leg 33 has progressed past the midpoint of conical-headed piston defeat 32 and is thereafter tensioned with a force acting positively to force pawl stub 37 in contact with the face of gear 8. Due to the previously described differential motion between sleeve 9' and gear 3, pawl structure 34 and sequentially shaft 22 will begin to rotate relative to sleeve 9.

In Fig. 6 are depicted in dashed lines the eccentric circleof travel 52 of the outer edge of pawl stub 36 or 37 and the concentric circle of travel 53 .of the outer extremity of pawl slot 40 taken with respect to primary axis 19. It may be. seen that the outer extremity ofpawl slot'40 lies on circle 53, and that circle 52 intersects circle 53 in two places, one of which lies within the end confines of pawl slot 40. Therefore, with the motion of sleeve 9 assumed clockwise and the relative motion of shaft 22 with respect to sleeve 9 assumed counterclockwise (as shown by arrows on circles 52, 53) pzu'i stub 37 will: drop into pawl slot 40 at some time before conclusionof of relative travel from its initial position. -Having dropped into slot 40, pawl stub 37 will shortly be picked up by the terminal side of said slot and thereafter carried around in synchronism with the rotation of sleeve 9. In other words, shaft 22 will now be locked in its new position relative to sleeve 9 as shown in Fig. 3.

Therefore, forward portion 11 of shaft 22 upon which 7 is mounted yoke structure 25 still rotates at a constant speed but in a conical pattern whose apex is at the intersection of axes 19, 29, and 60. If the device engaging yoke structure 25 at bearings 27, 28 is, as shown in Fig. 1, constrained to oscillate about axis 60, yoke structure 25 will be made to oscillate about axis 29, body 14 thereof moving in and out of the plane of the drawing of Fig. 3; and axis 29 along with the reflector 56 will be made to oscillate about axis 60. These two directions of oscillation, it will be seen, are components of the circular path described by the rearwardlydirected body portion 14 of yoke 25. As a-result the antenna reflector will describe the up and down oscillatory motion which is the important component :of the previously mentioned scanning pattern during search.

It will be obvious that in order for the mechanism 'to impart'a conical motion to an associated device, it

is necessary only to attach said device to the forward portion 11 of shaft 22 without incorporating yoke 25 therein or restraining the device about an axis 60 as previously described. 4 I

Although the antenna reflector support structure can be designed so that there are no forces reflected back into the drive unit from the induced oscillatory motion thereof, there may be an unbalanced effect due to the fact that the parts within the drive mechanism itself are not symmetrical. In this regard, dynamic balancing structure 15 is important. As the drive mechanism operates to induce oscillation in the associated device, balls 1.7 will orient themselves in race 18 in such a fashion as to counteract any unbalanced force and thereby minimize vibration.

If it is desired to restore the conditions under which there is no motion of the yoke structure, it-is only necessary to rotate lever 46 in the opposite direction. Thereafter the sequence of events concerning pawl-structure 34, cam 42, lands 41, and pawl slot 40 takes place. After a short interval of time, shaft 22 will have been rotated an additional 180 with respect to sleeve 9 to the posi tion originally occupied as indicated 'in Fig. 2. The mechanism will then be returned to the neutral or tracking position. I i

It is important to note that the shift from drive to neutral operation may be accomplished in less than onehalf second without interrupting primary power source due to the rapid rotation of sleeve 9 and associated parts.

Although the invention has been described and illus trated in detail, it is 'to be clearly understood that the same is by way of illustration and example only .andis not to be taken by way of limitation; the spirit and 'scope of this invention being limited only by the terms of the appended claims.

We claim:

1. A drive mechanism for causing an associated device to describe a selectable conical motion comprising a sleeve mounted for rotation about a primary axis and having a bore whose longitudinal axis intersects'zsaid primary axis, a shaft having afirst portion extending outwardly of said sleeve, selectively coaxial with said primary axis and a second portion rotatablyf mounted 2. A drive mechanism for causing an associated device to describe a selectable conical motion comprising a sleeve mounted for rotation about a primary axis and having a bore whose longitudinal axis intersects said primary axis at a point externally of said sleeve, a shaft having a first portion extending outwardly of said sleeve selectively coaxial with said primary axis and a second portionrotatably mounted in said bore offset axially from said first portion and disposed at the same angle to said first portion as said longitudinal axis makes with said primary axis, releasable locking means for preventing relative rotation of said sleeve and said shaft, driving means for imparting rotation to said sleeve, automatic actuating means for releasing and engaging said locking means, and a second driving means for selectively imparting rotation to said shaft relative to the rotation imparted to said sleeve, whereby said sleeve and said first portion are coaxial said first portion is maintained in a neutral position, and when said sleeve and said first portion are noncoaxial a conical motion is imparted to said first portion.

3. A drive mechanism for causing an associated device to describe a selectable conical motion comprising a shaft having a first portion and a second portion integral With said first portion but axially offset therefrom and with its longitudinal axis angularly disposed to and intersecting the primary axis of said drive mechanism at a point, a sleeve mounted for rotation about said primary axis and having an angularly disposed bore for rotatably receiving said second portion said sleeve being coaxial with said first portion when said sleeve and said second portion are in one of a plurality of selectable relative positions, releasable locking means for preventing relative rotation of said sleeve and said second portion when they are in said one and other of said selectable relative positions, driving means for imparting rotation to said sleeve, and a yoke having a main body rotatably mounted on said first portion and mounting arms on said yoke, said yoke being rotatable about a third axis which is coplanar with and intersecting said longitudinal and said primary axes at said point and which is normal to said primary axis when said sleeve and said second portion are in said one position, whereby when said sleeve and said second portion are in said one position said yoke is maintained in a neutral position, and when said sleeve and said second portion are in any of said other of said relative positions a conical motion is imparted to said yoke.

4. A drive mechanism for causing an antenna reflector to describe a selectable conical motion comprising a shaft having a first portion and a second portion integral with said first portion but axially offset therefrom and with-its longitudinal axis-angularly disposed to and intersecting-the primary axis of said drive mechanism at a with said first portion, releasable locking means for selectively preventing relative rotation of said sleeve and said second portion, driving means for imparting rotation to said sleeve, a yoke having a main body rotatably mounted on said first portion and mounting arms on said yoke, said yoke being rotatable about a third axis which is coplanar with and intersecting said longitudinal and said primary axes at said point and which is normal to said primary axis when said sleeve and said first portion are coaxial, and dynamic balancing means for preventing the transmission of undesirable forces to said yoke, said dynamic balancing means being an annular race mounted on said sleeve coaxial therewith and containing balls free to move 7 in said race for opposing said undesirable forces whereby and said first portion are coaxial said first portionis maintained in a neutral position,-andwhen said sleeve and said first portion are noncoaxial a conical-motion is imparted to said first portion.

when said sleeve and said first portion arecoaxial said yoke is maintained in a neutral position, and when said sleeve and said first portion are noncoaxial a conical mo tion is imparted to said yoke. i

5. A drive mechanism for causing an associated device to describe a selectable conical motion comprisinga shaft 7 having a first portion and a second portion integral with said first portion but axially offset therefrornand with its longitudinal axis angularly disposed to and intersecting the primary axis of said drive mechanism at a point, a sleeve mounted for rotation about asid primary axis and having an angularly disposed bore for rotatably receiving said second portion, said sleeve being coaxial with said first portion when said sleeve and said second portion are in one of a plurality of selectable relative positions, releasable locking means for preventing relative rotation of said sleeve and said second portion when they are in said one and other of said selectable relative positions, driving means for imparting rotation to said sleeve, a yoke having a main body rotatably mounted on said first portion and mounting arms on said yoke, said yoke being rotatable about a third axis which is coplanar with and intersecting said longitudinal and said primary axes at said point and which is normalto said primary axis when said sleeve and said second portion are in said one position, and automatic actuating means for releasing and engaging said locking means whereby when said -sleeve and said second portion are in said one position said yoke is maintained in a neutral position, and when said sleeve and said second portion are in any of said other of said relative positions a conical motion is imparted to saidyoke.

6. A drive mechanism for causing anassociated device to describe a selectable conical motion comprising a shaft having a first portion and a second portion integral with said first portion but axially oifset therefrom and with its longitudinal axis angularly disposed to and intersecting the primary axis of said drive mechanism at a point, a sleeve mounted for rotation about said primary axis and having an angularly disposed bore for rotatably receiving said second portion, said sleeve being coaxial with said first portion when said sleeve and said second portion are in one of a plurality of selectable relative positions, releasable locking means for preventing relative rotation of said sleeve and said second portion when they are in said one and other of said selectable relative positions, driving means for imparting rotation to said sleeve, a yoke having a main body rotatably mounted on said first portion and mounting arms on said yoke, said yoke being rotatable about a third axiswhich is coplanar with and intersecting said longitudinal and said primary axes at said point and which is normal to said primary axis when said sleeve and said second portion are in said one position, automatic actuating means for releasing and engaging said locking means, and second driving means for selectively imparting rotation to said shaft relative to the rotation imparted to said sleeve whereby when said sleeve and said second portion arein said onepositionsaidyoke is maintained ina neutral position, and when said sleeve and said second portion are in any of said other ofsaid relative positions a conical motion is imparted to said yoke.

7. A drive mechanism for causing anassociated device to describe a selectable conical motion comprising a shaft having a first portion and a second portion integral with said first portion but axially offset with its longitudinal axis angularly disposed to and intersecting the primary axis of said drive mechanism at a point, a sleeve mounted for rotation about said primary axis and having an angularly disposed bore for. rotatably receiving said second portion, said sleeve being coaxial with said first portion when said sleeve and said second portion are in one of a plurality of selectable relative positions, releasable locking means for preventing relative rotation of said sleeve and said second portion when they are in said one and other of said selectable relative positions, driving means for imparting rotation to said sleeve, a yoke having a main body rotatably mounted on said first portion and mounting arms on said yoke, sa-id yoke being rotatable about a third axis which is coplanar with and intersecting said longitudinal and said primary axes at said point and whichis normal to said primary axis when said sleeve and said second portion are in said one a rears position, antornatic actuating means for releasing and engaging aid ast n ns ne s c n driving wa o selectively imparting rotation to said shaft relative to the rotation imparted to said sleeve, and dynamic balancing means for preventing the transmission of undesirable forces to saidassociated device whereby when said sleeve and said second portionare in saidone position said yoke is maintained in a neutral posit-ion, and when said sleeve and said second portion are in any of said other of said relative positions a conical motion is imparted to said associated device.

8. A drive mechanism for causing an associated device to describe a selectable conical motion comprising a shaft having a first portion and a second portion integral with said first portion but axially offset therefrom and with its longitudinal agtis ,angularly disposed to and intersecting the primary axis of said drive mechanism at a point, a sleevemounted for rotation about said primary axis and having an angularly disposed bore for rotatably receiving said second portion, said sleeve being coaxial with said first portion when said sleeve and said second portion are in one of a plurality of selectable .relative positions, releasable locking means for preventing relative rotation of said sleeve and said second portion when they are in said one and other of said selectable relative positions, driving meansfor imparting rotation to said sleeve, a yoke having a main body rotatably mounted on said first portion and mounting arms on said yoke, said yoke being rotatable about a third axis which is coplanarwithand intersecting said longitudinal and said primary axes at said point and which is normal to said primary axis when said sleeve and said second portion are in said one position, said locking means being a plurality of pawls secured to said shaft for rotation therewith and an associated pawl slot in said sleeve whereby when said sleeve and said second portion are in said one position said yoke is maintained in a neutral position, and when said sleeve and said second portion are in any of saidother of said relative positions a conical motion is imparted to said yoke.

9. A drive mechanism for causing a n associated device to describe a selectable conical motion comprising a shaft having a first portion and a second port-ion integral with said first portion but axially offset therefrom and with its longitudinal axis angularly disposed to and intersecting the primary axis of said drive mechanism at a point, a sleeve mounted for rotation about said primary axis and having an angularly disposed bore for rotatably receiving said second portion, said sleeve being coaxial with said first portion when said sleeve and said second portion are in one of aplurality of selectable relative positions, releasable locking means for preventing relative rotation of said sleeve and said second portion when they are in said one and other of saidselectable relative positions, driving means for imparting rotation to said sleeve, a yoke having a main body rotatably mounted on said first portion and mounting arms on said yoke, said yoke eing rotatable about a third axis which is coplanar with and intersecting said longitudinal and said primary axes at said point and which is normal to said primary axis when said sleeve and said second portion are in said one position, and automatic actuating means for releasing and engaging said locking means, said locking means being a plurality of pawls secured to s'aid-shaft-for rotation therewith and an associated pawlslot in, said sleeve, said actuating means being selectively operative cams and associated cam stubs interconnected to said pawls whereby when said sleeve and said second portion are in said one position said yoke is maintained in a neutral position, and when said sleeve and said second portion are in any of said other of said relative positions a conical motion isimparted to said yoke.

"10. A drivemechanismuforgcausing an associatedidevice to describe a selectable conical motion comprising a shaft having a first portion and a second portion integral with said first portion but axially offset therefrom and with its longitudinal axis angularly disposed to and intersecting the primary axis of said drive mechanism at a point, a sleeve mounted for rotation about said primary axis and having an angularly disposed bore for rotatably receiving said second portion said sleeve being coaxial with said first portion when said sleeve and said second portion are in one of a plurality of selectable relative positions, releasable locking means for preventing relative rotation of said sleeve and said second portion when they are in said one and other of said selectable relative positions, driving means for imparting rotation to said sleeve, a yoke having a main body rotatablymounted on said first portion and mounting arms on said yoke, said yoke being rotatable about a third axis which is coplanar with and intersecting said longitudinal and said primary axes at said point and which is normal to said primary axis when said sleeve and said second portion are in said one position, automatic actuating means for releasing and engaging said locking means, second driving means for selectively imparting rotation to said shaft relative to the rotation imparted to said sleeve, and dynamic balancing means for preventing the transmission of undesirable forces to said yoke, said locking means being a plurality of pawls secured to said shaft for rotation therewith and an associated pawl slot in said sleeve, said actuating means being selectively operative cams and associated cam stubs interconnected to said pawls, said second driving means being differentially rotated relative to said sleeve and relative to said shaft by the interaction of said cams, said stubs, said pawls, and said dynamic balancing means being an annular race mounted on said sleeve coaxial therewith and containing balls free to move in said race for opposing said undesirable forces whereby when said sleeve and said second portion are in said one position said yoke is maintained in a neutral position, and when said sleeve and said second portion are in any of said other of said relative positions a conical motion is imparted to said yoke.

No references cited. 

